Traditionally, LDO regulators include an amplifier and a closed-loop feedback to provide appropriate output levels. The limited frequency response, however, implies the inefficiency of high-speed applications, and, the closed loop may induce instability when the output is connected to large-capacitance or low-current loadings. Further, in the advance process node (e.g., 0.13 μm or below), the specified voltage levels are needed to enlarge the supply voltage or to clamp the voltage range for certain purposes.
Like reference symbols in the various drawings indicate like elements.